1. Field of the Invention
The invention relates to a deceleration control apparatus for a vehicle.
2. Description of the Related Art
There are known technologies for performing deceleration control for a vehicle based on information concerning the configuration of the road ahead of a host vehicle (e.g. the curvature radius of an upcoming curve, and the distance between the host vehicle and the starting point of the curve).
Each of Japanese Patent Application Publication No. JP-A-08-194889 and Japanese Patent Application Publication No. JP-A-2003-202071 describes the technology related to a control apparatus for dealing with the state of the road ahead of a host vehicle. Japanese Patent Application Publication No. JP-A-08-194889 describes the technology in which there are provided determining means, and alarm means. When recognizing that there is a curve in the road ahead of the vehicle based on the road information stored in advance, the determining means determines whether the present vehicle speed is too high for the host vehicle to appropriately go round this upcoming curve. The alarm means raises an alarm, if the determining means determines that the present vehicle speed is too high. The determining means is configured to determine the degree to which the present vehicle speed exceeds the appropriate vehicle speed for the upcoming curve, if the present vehicle speed is too high for the host vehicle to appropriately go round the upcoming curve. The alarm means is configured to raise different types of alarms depending on the degree to which the present vehicle speed exceeds the appropriate vehicle speed for the upcoming curve. With this technology, the driver can recognize the degree to which the present vehicle speed exceeds the appropriate vehicle speed for the upcoming curve depending on the type of an alarm.
Japanese Patent Application Publication No. JP-A-08-194889 merely describes an alarm device that raises an alarm based on the degree to which the present vehicle speed exceeds the appropriate vehicle speed for the upcoming curve. This publication does not describe the technology where deceleration control is performed using the deceleration calculated based on the distance to the starting point of the upcoming curve, the curvature radius of the curve, and the present vehicle speed. Namely, although Japanese Patent Application Publication No. JP-A-08-194889 describes the vehicle speed control (e.g. downshift control and throttle control), the vehicle speed control is basically performed just to urge the driver to decelerate the vehicle by means other than voice if the driver does not decelerate the vehicle even after an alarm is raised by voice (this publication merely describes the technology where, if the degree, to which the present vehicle speed exceeds the appropriate vehicle speed for the upcoming curve, is equal to or higher than a predetermined degree, the shift speed is reduced by one level). This publication does not describe the technology for performing the deceleration control based on the deceleration calculated as a value variable based on the curvature radius of the upcoming curve, and the like.
It is desirable that the deceleration control provide drive assist according to an intention of the driver and enhance driving convenience for the driver.